Given Crowthorne has recently written a fairly comprehensive review , I don't intend going into too much detail. I have to say I agree with most of the assessment of both zoos. Crowthorne said she preferred Duisburg and in terms of species, I think I agree, it had the 'wow' factor for me in the shape of many species I hadn't seen in decades ( in the days of London in the 70s/80s). Cologne was great too, but I think after visiting the Berlin zoos last year, it didn't seem quite as great as it might have done!
Duisburg
Highlight Species
The obvious ! *
Wombat
Tasmanian Devil
Koala
Echidna
Roloway Monkey
Kori Bustard
White nosed Guenon
My first bottle nosed dolphin since Whipsnade , very early 80s
Highlight enclosures
Tiger
Lynx
Fossa
Andean Bear
Rio Negro
Tasmanian Devil
Poor enclosures
Orangutan outdoors, possibly only rivalled by Dudley for worst I've seen this decade!
Cologne
Species
Red Howler
Rufous Elephant Shrew*
Sun squirrel *
Ring tailed mongoose
Red Spanked Douc *
Matschies Tree Kangaroo *
southern Bald Ibis *
Grizzly Bear
Musk Ox
Weddell's Tamarin *
* = lifer
Highlight exhibits
Regenwald
Elephants - amazing!
All Great Ape exhibits better than zoo Berlin
Hippodom
Aquarium , not Berlin, but never seen so many monitor species in one zoo, 10+?
Poor exhibits
Ex Ratel exhibit - appalling !!!! The meerkat enclosure must be 50x the size, probably 100
Black Rhino - never viewed through dirty glass before
Red Howler - 3 enclosures , none making the most of this rarity!
Penguins - don't think I've seen much worse anywhere in UK!
May remember more later and add them!
What I should say if either of these zoos were in the UK , they would make my top 5 comfortably .